i recently read "Man's Search for Meaning" by Viktor Frankl, and he talks about this very thing in his book. Dr. Frankl was a psychiatrist and Holocaust survivor. After the war, he developed an existential therapy method that he called 'logotherapy,' and the basic premise of the therapy was that everyone needs to find meaning and purpose in their life to be psychologically healthy. He said that he noted in the camps that those who survived had something to live for. Those who did not have something, or who gave up on that something, quickly perished. He also said that those who survived that found what they had been living for was gone (like a loved one or a family member) also died.

The meaning for each of us is quite different. For one person, it might be their family, another it would be their life's work, another it might be helping others, or even making money. No one but your friend knows what her purpose is. If it is serious enough, she may need to seek some help in discovering her meaning.